1. Field of the Invention
The present invention relates to an unlocking controller of an irreversible rotary transmission system for control of the rotation position.
2. Background Information
A rotation transmission system for carrying out control of the rotation position works as follows: the system transmits the torque from the actuator to the control subject, and, when the control subject reaches the target rotation position, the control subject holds the actuator in the stop state, and the control subject holds the target rotation position.
However, depending on the control subject, when the actuator that should hold the control subject at the target rotation position is held in the stop state, a reactive force (the load torque) in a prescribed direction may be reversely input to the actuator.
In this case, in order to hold the actuator that should hold the control subject at the target rotation position in the stop state, it is necessary to keep applying driving control to the actuator so that a torque counteracting the reversely input force having the same magnitude as that of the reactive force (the load torque) in a prescribed direction is output, and the driving energy of the actuator increases. This is undesirable. In addition, the control operation becomes complicated, and this is also undesirable.
As a measure for solving the problem related to the reactive force (the load torque) reversely input to the actuator, in the prior art, as described in Japanese Laid-Open Patent Application No. 2001-003773, control is carried out on the nonlinear reactive force (the load torque) that varies corresponding to each rotation position (the rotational angle) of the control subject by feed forward compensation of the actuator torque corresponding to the rotation position (the rotational angle) of the control subject detected successively. Consequently, the control operation is complicated for the technology coping with the problems.
On the other hand, as a scheme to solve the previously described problem, to increase in the driving energy of the actuator, people have proposed the following scheme: a control system is formed in an irreversible rotary transmission system; that is, an irreversible rotation transmission element is inserted, and the irreversible rotation transmission element works as follows: in the transmission-off state, when the torque is not transmitted from the actuator to the control subject, the transmission assumes a lock state for the reactive force (the load torque) of the control subject, so that transmission of the reactive force (the load torque) to the actuator is prohibited, and the reactive force (they load torque) that would be reversely input to the actuator cannot go to the actuator. As a result, there is no need to keep applying the driving control on the actuator.
However, in this scheme, when the control transmits the torque from the actuator to the control subject, first of all, an unlocking torque in the rotational direction of the actuator should be applied on the irreversible rotation transmission element so that the irreversible rotation transmission element assumes the lock released state with this driving control of the actuator, and then the torque of the actuator can be transmitted via the irreversible rotation transmission element to the control subject.
In this case, in order to decrease the unlocking torque, in the prior art, as described in Japanese Laid-Open Patent Application No. 2007-002934, people have proposed a scheme in which, by applying a high frequency vibration, the frictional force for forming the lock state is decreased.
When an irreversible rotary transmission system is constructed by inserting an irreversible rotation transmission element, for the control system from the actuator to the control subject, the following problems take place for the configurations described in the Japanese Laid-Open Patent Application No. 2001-003773 and Japanese Laid-Open Patent Application No. 2007-002934.
That is, when the rotation position is controlled, as described above, first of all, an unlocking torque in the actuator rotational direction should be applied on the irreversible rotation transmission element to set the irreversible rotation transmission element in the lock released state.
However, during the period when unlocking has not yet been completed and the irreversible rotation transmission element has not yet been locked, if the configuration described in Japanese Laid-Open Patent Application No. 2001-003773 is adopted, even when the feed forward compensation is made on the reactive force (the load torque) from the control subject reversely input to the actuator, as the reactive force (the load torque) has not yet reached the actuator, the effects asserted by Japanese Laid-Open Patent Application No. 2001-003773 cannot be realized.
In addition, during the period when the irreversible rotation transmission element has not yet been in the locked state, according to the configuration described in Japanese Laid-Open Patent Application No. 2001-003773, a torque compensation may be carried out in the direction opposite to the unlocking torque, and the output of the feedback compensator is held for awaiting the arrival of the unlocking torque, so that a delay takes place in rise of the response; as the output of the feedback compensator is held, the response after unlocking degrades. This is undesirable.
On the other hand, when the configuration of the Japanese Laid-Open Patent Application No. 2007-002934 for decreasing the unlocking torque is adopted, as a high frequency vibration is applied to decrease the frictional force for holding the lock state, the desired effect cannot be realized.
That is, when the reactive force (the load torque) from the control subject is high, the engagement members in the lock mechanism in the irreversible rotation transmission element are forcibly engaged with each other; when the actuator is driven in the same direction as that of the reactive force (the load torque) in controlling the rotation position, if only the high frequency vibration is applied on the lock mechanism of the irreversible rotation transmission element according to the configuration of Japanese Laid-Open Patent Application No. 2007-002934, the unlocking torque cannot be significantly decreased, so that the irreversible rotation transmission element cannot quickly release the lock; thus, a significant delay in response takes place. This is undesirable.
The purpose of the present invention is to solve the previously described problems of the prior art described in Japanese Laid-Open Patent Application No. 2001-003773 and Japanese Laid-Open Patent Application No. 2007-002934 recited above by providing a unlocking controller of the irreversible rotary transmission system, wherein the magnitude of the unlocking torque on the irreversible rotation transmission element is changed corresponding to the actuator rotational direction when lock is released with respect to the direction of the reactive force (the load torque) from the control subject, so that even when the actuator rotates in the direction that causes the problem of delaying the response in unlocking, the unlocking response still can be maintained as desired.
In order to realize the purpose described above, the present invention provides an unlocking controller of the irreversible rotary transmission system with the following configuration: an input shaft that inputs the torque from the actuator; an output shaft that outputs the torque from the input shaft; and an irreversible rotation transmission element with the following features: the irreversible rotation transmission element is arranged between the input shaft and the output shaft described above; the irreversible rotation transmission element enacts driving control of the actuator described above so that, when the torque is transmitted from the input shaft to the output shaft, the torque described above is greater than the unlocking torque, so that the irreversible rotation transmission element assumes the lock released state that allows transmission of the torque described above; on the other hand, in the transmission-off state when the torque is not transmitted from the input shaft to the output shaft, the irreversible rotation transmission element is locked by the load torque of the output shaft, so that transmission of the load torque of the output shaft to the input shaft is prohibited.
According to the present invention, as a characteristic feature of the configuration, for the irreversible rotary transmission system described above, an input shaft rotation direction determination means when the lock is released and an unlocking torque setting means are arranged having the following features.
The former part, that is, the input shaft rotation direction determination means when the lock is released determines whether the input shaft rotational direction is the same as, or opposite to, the direction of the output shaft load torque.
The latter part, that is, the unlocking torque setting means responds to the result of the determination of the input shaft rotation direction determination means when the lock is released; when the input shaft rotational direction when lock is released is the same as the direction of the output shaft load torque, the unlocking torque is higher than that when they are opposite to each other.
For the unlocking controller of the irreversible rotary transmission system of the present invention, the unlocking torque when the input shaft rotational direction when the lock is released is the same as the direction of the output shaft load torque and is higher than that when the directions are opposite to each other. As a result, the following operation and effects can be realized.
When the input shaft rotational direction when the lock is released is the same as the direction of the output shaft load torque, and the lock is released in the same direction as the load torque applied on the output shaft, the engagement member, which has a higher engagement gripping force of the irreversible rotation transmission element under the influence of the high load torque applied on the output shaft, is pressed in the unlocking direction to release the lock of the irreversible rotation transmission element.
According to the present invention, in this case, because the unlocking torque is higher, even when the actuator rotates in the direction that used to be a problem due to the delay in the response in unlocking, the higher unlocking torque can maintain the unlocking response as desired, so that it is possible to prevent the problem related to the unlocking response described above.